Hydrangea plant named ‘H218915’

ABSTRACT

A new and distinct cultivar of  Hydrangea  plant named ‘H218915’, characterized by its upright and uniformly mounded plant habit; vigorous growth habit and rapid growth rate; freely branching habit with strong, thick and sturdy stems; freely and uniformly flowering habit; lacecap-type inflorescences with numerous double sterile flowers that are white in color; and good postproduction longevity.

Botanical designation: Hydrangea macrophylla.

Cultivar denomination: ‘H218915’.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct cultivar of Hydrangea plant, botanically known as Hydrangea macrophylla, commercially referred to as a lacecap-type Hydrangea and hereinafter referred to by the name ‘H218915’.

The new Hydrangea plant is a product of a planned breeding program conducted by the Inventor in De Kwakel, The Netherlands and Lengerich, Germany. The objective of the breeding program was to create new strong and freely-branching Hydrangea plants with strong sturdy stems, uniform flowering habit, large inflorescences with numerous showy sterile flowers, attractive sterile flower color and good postproduction longevity.

The new Hydrangea plant originated from a self-pollination made by the Inventor in March, 2013 in De Kwakel, The Netherlands, of a proprietary selection of Hydrangea macrophylla identified as code number 11-0322-001, not patented. The new Hydrangea plant was discovered and selected by the Inventor as a single flowering plant from within the progeny of the stated self-pollination in a controlled greenhouse environment in Lengerich, Germany in March, 2014.

Asexual reproduction of the new Hydrangea plant by vegetative tip cuttings in a controlled environment in De Kwakel, The Netherlands since April, 2015 has shown that the unique features of this new Hydrangea plant are stable and reproduced true to type in successive generations.

SUMMARY OF THE INVENTION

Plants of the new Hydrangea have not been observed under all possible combinations of environmental conditions and cultural practices. The phenotype may vary somewhat with variations in environmental conditions such as temperature and light intensity without, however, any variance in genotype.

The following traits have been repeatedly observed and are determined to be the unique characteristics of ‘H218915’. These characteristics in combination distinguish ‘H218915’ as a new and distinct Hydrangea plant:

-   -   1. Upright and uniformly mounded plant habit.     -   2. Vigorous growth habit and rapid growth rate.     -   3. Freely branching habit with strong, thick and sturdy stems.     -   4. Freely and uniformly flowering habit.     -   5. Lacecap-type inflorescences with numerous double sterile         flowers that are white in color.     -   6. Good postproduction longevity.

Plants of the new Hydrangea can be compared to plants of the female parent selection. Plants of the new Hydrangea differ primarily from plants of the female parent selection in sterile flower type as plants of the new Hydrangea have double sterile flowers whereas plants of the female parent selection have single sterile flowers.

Plants of the new Hydrangea can be compared to plants of the male parent selection. Plants of the new Hydrangea differ primarily from plants of the male parent selection in sterile flower type as plants of the new Hydrangea have double sterile flowers whereas plants of the male parent selection have single sterile flowers.

Plants of the new Hydrangea can be compared to plants of the Hydrangea macrophylla ‘H212905’, disclosed in U.S. Plant Pat. No. 26,508. In side-by-side comparisons, plants of the new Hydrangea differ primarily from plants of ‘H212905’ in the following characteristics:

-   -   1. Plants of the new Hydrangea are broader than plants of         ‘H212905’.     -   2. Plants of the new Hydrangea have smaller leaves than plants         of ‘H212905’.     -   3. Plants of the new Hydrangea have broader panicles than plants         of ‘H212905’.     -   4. Plants of the new Hydrangea have more sterile flowers per         panicle than plants of ‘H212905’.     -   5. Plants of the new Hydrangea have double sterile flowers         whereas plants of ‘H212905’ have single sterile flowers.     -   6. Plants of the new Hydrangea have not been observed to develop         fertile flowers whereas plants of ‘H212905’ develop fertile         flowers.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

The accompanying colored photographs illustrate the unique appearance of the new Hydrangea plant showing the colors as true as it is reasonably possible to obtain in colored reproductions of this type. Colors in the photographs may differ from the color values cited in the detailed botanical description which accurately describe the colors of the new Hydrangea plant.

The photograph on the first sheet is a side perspective view of a typical flowering plant of ‘H218915’.

The photograph on the second sheet is a close-up view of a typical inflorescence of ‘H218915’.

The photograph on the third sheet is a top perspective view of a typical flowering plant of ‘H218915’ that has been “blued” (left) that is, treated with aluminum sulfate, and a top perspective view of a typical flowering plant of ‘H218915’ that has not been “blued” (right) that is, not treated with aluminum sulfate.

DETAILED BOTANICAL DESCRIPTION

Plants used in the aforementioned photographs and in the following description were grown during the late spring and early summer in 13-cm containers in a glass-covered greenhouse in De Kwakel, The Netherlands and under cultural practices typical of commercial Hydrangea production. During the production of the plants, day and night temperatures averaged 17° C. Plants of the new Hydrangea were one year old when the photographs and description were taken. Plants of the new Hydrangea treated with aluminum sulfate to “blue” the inflorescences do not show any significant color changes. In the following description, color references are made to The Royal Horticultural Society Colour Chart, 2015 Edition, except where general terms of ordinary dictionary significance are used.

-   Botanical description: Hydrangea macrophylla ‘H218915’. -   Parentage:     -   -   Female, or seed, parent.—Proprietary selection of Hydrangea             macrophylla identified as code number 11-0322-001, not             patented.         -   Male, or pollen, parent.—Proprietary selection of Hydrangea             macrophylla identified as code number 11-0322-001, not             patented. -   Propagation:     -   -   Type cutting.—By vegetative tip cuttings.         -   Time to initiate roots, summer.—About two weeks at             temperatures about 23° C.         -   Time to initiate roots, winter.—About 18 days at             temperatures about 20° C.         -   Time to produce a rooted young plant, summer.—About four             weeks at temperatures about 23° C.         -   Time to produce a rooted young plant, winter.—About five             weeks at temperatures about 20° C.         -   Root description.—Thick; typically whitish brown in color,             actual color of the roots is dependent on substrate             composition, water quality, fertilizer type and formulation,             substrate temperature and physiological age of roots.         -   Rooting habit.—Freely branching; dense. -   Plant description:     -   -   Plant and growth habit.—Upright and uniformly mounded plant             habit; strong and sturdy stems; rapid growth rate and             vigorous growth habit.         -   Plant height.—About 25 cm to 35 cm.         -   Plant diameter or area of spread.—About 45 cm to 50 cm. -   Lateral branch description:     -   -   Branching habit.—Freely branching habit; when pinched, about             eight lateral branches develop per plant.         -   Length.—About 20 cm to 25 cm.         -   Diameter.—About 5 mm to 7 mm.         -   Internode length.—About 2 cm to 5 cm.         -   Texture.—Smooth, glabrous; fully developed, woody.         -   Aspect.—Upright to slightly outwardly.         -   Strength.—Strong, sturdy.         -   Color.—When developing: Close to 144B; at internodes, close             to 185C; lenticels, close to 145C. Developed: Close to 144B;             at the internodes, close to 185C; when woody, close to 177C;             lenticels, close to 145C. -   Leaf description:     -   -   Arrangement.—Opposite, simple.         -   Length.—About 7 cm to 10 cm.         -   Width.—About 5 cm to 7 cm.         -   Shape.—Ovate.         -   Apex.—Cuspidate.         -   Base.—Obtuse.         -   Margin.—Dentate to serrate.         -   Texture, upper surface.—Smooth, glabrous.         -   Texture, lower surface.—Rugose, glabrous.         -   Venation pattern.—Pinnate.         -   Color.—Developing and fully expanded leaves, upper surface:             Close to 137A; venation, close to 146D. Developing and fully             expanded leaves, lower surface: Close to 137D; venation,             close to 146D.         -   Petioles.—Length: About 1.5 cm to 2 cm. Diameter: About             3 mm. Texture, upper and lower surfaces: Smooth, glabrous.             Color, upper and lower surfaces: Close to 146D. -   Flower description:     -   -   Flower type and habit.—Double showy sterile flowers arranged             on lacecap-type terminal panicles; to date, fertile flower             development has not been observed on plants of the new             Hydrangea; panicles flattened globular in shape; flowers             face upright to outwardly depending on their position in the             inflorescence.         -   Fragrance.—None detected.         -   Natural flowering season.—Plants begin flowering about nine             to 14 months after planting; flowering begins in the early             summer and is continuous throughout the summer in Northern             Europe.         -   Flower longevity.—Sterile flowers last about four months on             the plant, sterile flowers persistent.         -   Quantity of flowers.—Freely flowering habit; about 280             sterile flowers develop per panicle.         -   Panicle height.—About 6 cm to 8 cm.         -   Panicle diameter.—About 20 cm to 23 cm.         -   Sterile flower buds.—Length: About 3 mm. Diameter: About             3 mm. Shape: Spherical. Color: Close to 145B.         -   Sterile flower diameter.—About 3.5 cm to 4 cm.         -   Sterile flower depth (height).—About 1 cm.         -   Petals, sterile flowers.—To date, petal development has not             been observed on plants of the new Hydrangea.         -   Sepals, sterile flowers.—Quantity and arrangement: About 14             in about three whorls. Length, outer whorl: About 2 cm to             2.5 cm. Length, inner whorls: About 1 cm to 1.5 cm. Width,             outer whorl: About 1.5 cm to 2 cm. Width, inner whorls:             About 1 cm. Shape: Ovate. Apex: Obtuse to acute. Base:             Obtuse. Margin: Entire. Texture, upper and lower surfaces:             Smooth, glabrous. Color: When opening, upper and lower             surfaces: Close to 145D and 145B. Fully opened, upper             surface: Close to NN155D; with development, color becoming             closer to 145B; when “blued”, inner whorls becoming closer             to 155B. Fully opened, lower surface: Close to NN155D; with             development, color becoming closer to 145C.         -   Pedicels, sterile flowers.—Length: About 3 cm to 4 cm.             Diameter: About 2 mm. Strength: Strong. Aspect: Erect to             about 45° from vertical. Texture: Smooth, glabrous. Color:             Close to NN155D.         -   Reproductive organs, sterile flowers.—Stamens: To date,             stamen development has not been observed on plants of the             new Hydrangea. Pistils: Pistil quantity per flower: About             three or four. Pistil length: About 1 mm. Stigma shape:             Conical. Stigma color: Close to 155A. Style length: About             1 mm. Style color: Close to 155A. Ovary color: Close to             155A.         -   Seeds.—To date, seed development has not been observed on             plants of the new Hydrangea. -   Pathogen & pest resistance: Under commercial production conditions,     plants of the new Hydrangea have not been observed to be resistant     to pathogens and pests common to Hydrangea plants to date. -   Temperature tolerance: Plants of the new Hydrangea have been shown     to be tolerant to temperatures ranging from about 3° C. to about 38°     C. 

It is claimed:
 1. A new and distinct Hydrangea plant named ‘H218915’ as illustrated and described. 